FIG. 1A is an illustration of our universal ripper miner disclosed in U.S. Pat. No. 4,501,448 to Roger J. Morrell and David A. Larson, assigned to the United States of America as represented by the Secretary of the Interior. Our prior ripper miner machine includes two hydraulically operated pistons 201 and 202 with their movable and extendable piston rods 203 an 204, respectively, being attached to the cutter head 206. At one end, the pistons are pivotally attached by roller shafts 220 and 221 to the machine's main frame 205 and at the other end to the movable cutter head by roller shafts 222 and 223. A center shaft 207 allows the cutter head 206 with its drag bit 208 to rotate in an arcuate path as the attached two piston rods are reciprocated by a power source within their respective movable pistons. The cutter head rotates in an arcuate vertical path through approximately 185.degree. during its cutting swing or cycle. As the rock is cut loose from the face by drag bit 208, the cuttings are continuously collected in the hopper 209 section of the cutter head which moves in unison with the drag bit. At the end of the cutting swing, an opening 210 in the hopper allows the cuttings to drop through chute 211 into an external bin 212. From this bin, the cuttings are fed onto a conventional conveyor 213 and moved to the end of the machine and then into the mine haulage system. After each vertical cutting upswing, the bit is returned to its original starting position. The main frame 205 and cutter head are then rotated horizontally by the rotary table 214 into position for the next cutting swing. The roof jack assembly 215 pushes against the roof to lock the machine firmly in place during the cutting operation. After the bit has cut across the entire face of the heading, the main frame and cutting head are advanced forward (i.e., to the left in FIG. 1A) for the next cutting cycle by the two advance pistons 225 and 226. These pistons slide the entire machine, which is mounted to the base plate 219, along the walking beams 217 and 218. After three to four advance cycles, the machine is raised up off of the ground by jacks (not shown) the advanced pistons retracted, and the machine is ready for another series of cutting advances at a new location to the right or left of its previous cutting cycle. Thus, it is to be noted that the machine advances forward between a series of individual cutting cycles and the machine is rotated horizontally after each of its individual cutting cycles or swings.
The drag cutter 208 consists of a bit insert and a bit holder, the bit holder resisting the cutting forces and holding the bit insert in place. The bit insert does the actual rock cutting. It is held in place on the holder by bolting, or by clamping or brazing. The bit insert has only one cutting edge requiring frequent resharpening, depending upon the hardness of rock being mined, causing down time during resharpening.
It is accordingly one object of the present invention to provide a cutter bit for mining machines generally, and the ripper miner disclosed above in particular, that has multiple cutting edges.
Another object of the invention is to provide the multiple cutting edge bit with a capability of being easily and quickly indexed upon the bit holder to expose a fresh cutting edge.
Another object of the invention is to provide a bit indexing system that automatically indexes the bit to expose a fresh cutting edge without manual intervention.
As mentioned above, our prior universal ripper miner disclosed in FIG. 1A is only capable of cutting operation in the upstroke. Thereby, valuable mining time is lost each time the cutter head 206 reaches its upper end of cutting stroke through the period it is lowered by pistons 201 and 202 to its bottommost position where it is repositioned to execute the next upward cutting stroke.
Another object of the present invention is to provide a cutter head of a mining machine with a bi-directional cutter enabling the machine to mine rock in both upward and downward cutting strokes.
Another object of the invention is to provide a mining machine in general, and our ripper miner disclosed above in particular, with a bi-directional cutter that mines rock in both the upstroke and the downstroke and which has the further capability of utilizing a cutting bit with multiple cutting edges.
Still a further object of the present invention is to provide a cutter head with a multi-holder arrangement allowing a plurality of bits to be mounted upon the cutter head to improve mining efficiency.
Still a further object of the invention is to provide an on-board bit resharpening system that is capable of sharpening the cutter bit(s) at the end of an upward or downward cutting cycle.